- published: 20 Jun 2014
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The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 Mya (million years ago), to the beginning of the Carboniferous Period, about 358.9. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish". The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating almost every known aquatic environment.
The ancestors of all tetrapods began adapting to walking on land, their strong pectoral and pelvic fins gradually evolving into legs. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician. The first ammonite mollusks appeared. Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placoderms, and all trilobites, save for a few species of the order Proetida.
Ciara: The Evolution (simply known as The Evolution) is the second studio album by American recording artist Ciara, released on December 5, 2006, by LaFace Records. The album is separated into five sections, with each showcasing a different side of Ciara's artistry. The first features crunk&B and uptempo records, which mainly deal with feminine independence, while its successor, entitled The Evolution of Music features ballads dealing with the positives and struggles of love. The Evolution of Dance features dance tracks, The Evolution of Fashion deals with self-expression, while the last, entitled The Evolution of C, features tracks that discuss how Ciara has evolved as a person since the start of her career.
The album was seen as a coming of age project for the singer, as it featured songs with more substance than her last effort. It deals with Ciara's experiences after being in the public eye for the two years prior to the album's release. The tracks are also said to be geared toward a more urban audience. Ciara was the executive producer of the album and enlisted production from Phillana Williams, Antwoine Collins, Brian Kennedy, Bryan-Michael Cox, Calvo Da Gr8, Dallas Austin, Jazze Pha, Kendrick Dean, Lil Jon, Mr. Collipark, The Neptunes, Polow da Don, Rodney Jerkins, The Clutch, will.i.am, among others, and featured guest appearances from 50 Cent and Chamillionaire. Ciara also co-wrote and co-produces most of the songs.
The most prolific time period for the evolution and proliferation of fish was the Devonian Period. Jawless fish, sharks, coelacanths, placoderms, and many more all flourished. Origins of the coelacanth paper(which was helpful): http://www.marine.fks.ed.jp/images/coela/sympo/p1-3.pdf Polish Tetrapod Tracks: http://www.nature.com/nature/journal/v463/n7277/abs/nature08623.html
The evolution of fish began about 530 million years ago during the Cambrian explosion. Early fish from the fossil record are represented by a group of small, jawless, armoured fish known as ostracoderms. Jawless fish lineages are mostly extinct. An extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placoderm fossils. The diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, or a combination of factors. The evolution of fish is not studied as a single event since fish do not represent a monophyletic group but a paraphyletic one (by exclusion of the tetrapods).
The first major groups of amphibians developed in the Devonian period, around 370 million years ago, from lobe-finned fish which were similar to the modern coelacanth and lungfish. These ancient lobe-finned fish had evolved multi-jointed leg-like fins with digits that enabled them to crawl along the sea bottom. Some fish had developed primitive lungs to help them breathe air when the stagnant pools of the Devonian swamps were low in oxygen. They could also use their strong fins to hoist themselves out of the water and onto dry land if circumstances so required. Eventually, their bony fins would evolve into limbs and they would become the ancestors to all tetrapods, including modern amphibians, reptiles, birds, and mammals. Despite being able to crawl on land, many of these prehistoric tetr...
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 ± 3.2 Mya (million years ago), to the beginning of the Carboniferous Period, about 358.9 ± 0.4. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the...
Visit: http://www.spaceandintelligence.com Racism, denialism or creationism will not be tolerated. The Permian--Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years. Presented by To...
My presentation of the Devonian Period. please rate & comment.
Let's just be glad they chose the Jurassic period. See more http://www.collegehumor.com LIKE us on: http://www.facebook.com/collegehumor FOLLOW us on: http://www.twitter.com/collegehumor FOLLOW us on: http://www.collegehumor.tumblr.com Subscribe to our new channel: CH2: https://www.youtube.com/ch2
NARRATED AUDIO VERSION! A centipede the size of an alligator? Yes...and there is more... - Mega Top Tens ----------------------------------------------------------------------------------------------------------- 10 Prehistoric Bugs That Could Seriously Mess You Up Just about everyone is frightened of arachnids—however the basic consolation is that creepy crawlies are likewise terrified of you. There's nothing very like the inclination prompted by an inconspicuous creepy crawly rushing over your arm, or by a little centipede escaping your shoe. In any case, imagine a scenario where that centipede were three feet long. A huge number of years prior, creatures like these were all over the place. Here are a couple of the most astonishing ancient bugs ever to walk—or if I say slither?— th...
A video I created about some really scary and bizarre prehistoric creatures that are like monsters. Watch the video to learn more :-) It includes: Argentavis (South America, Thunderbird legends of Native Americans), Dunkleosteus (Devonian period, jaws), Chalicothere (knuckles, like an ape, cross between a gorilla and a horse, Africa, Eurasia and North America, Eocene to Pliocene periods, vegetarian), Sea scorpion (eurypterids, Ordovician period), Mosasaur (lizards and snake, Cretaceous period), Doedicurus (armadillos, South America, Pleistocene), Elasmotherium (gigantic rhinoceros, Asia, Pliocene and Pleistocene periods), Megalania (Varanus priscus, gigantic lizard, Komodo Dragon, Australia during the Pleistocene), Pliosaur (Jurassic and early Cretaceous seas, Liopleurodon and Kronosaurus...